Energy Saving with Inverters

Substantial savings can be made by reducing the speed (where the application allows) at which a motor runs a pump, fan or other application.

Whilst inverters are now fitted on plant and equipment as it is installed, (or have since been retrofitted) there are still numerous examples where starters and other equipment are used to control a motor. By fitting an inverter (also called a drive) the motor speed can be controlled and therefore reduced where the application permits a reduction in speed. An example of where motor speeds can be reduced is in systems where mechanical forms of damping (e.g. in fan applications) are used to control air or product flow. Once an inverter has been fitted to the motor, the damping can be removed from the system and the motor speed reduced to give the required flow. The use of valves in pump systems (where valves are used to control the flow of fluids etc.) are another example where motor speed can be reduced and energy saved.

Due to the relationship between the speed a motor runs at and the power used, if the motor speed can be reduced by 10% it results in nearly a 30% reduction in the power used and a 15% reduction results in nearly a 40% reduction in power and therefore the costs of running the application. When considering the fact that a motor can use 100 times its purchase cost in electricity in its lifetime, the savings can be substantial, giving very attractive payback returns, typically within a year for many examples.

Energy saving with inverters – the RJW service

At RJW, we are able to provide the complete service, from the identification of opportunities, the calculation of paybacks, the supply of the correct, most suitable inverter (type and manufacturer), the design, building and fitting of the inverter within a control panel as well as the installation and commissioning:

Identification of opportunities – by carrying out a plant survey and analysing where the greatest savings can be made, based mainly on the motor size, usage (in terms of time) and motor application we are able to detail the best options for fitting an inverter.

Calculation of paybacks – by analysing the existing motor usage and efficiency characteristics and comparing it with the costs of running the same (or a high efficiency) motor with an inverter, we are able to provide accurate payback calculations from which to make an informed decision.

Supplying the correct inverter – as the approved distributor for a number of inverter manufacturers, we are able to match our customers requirements to the appropriate manufacturer and type of inverter, whether the principal factors are cost, rating or functionality within the inverter. If required, at this stage we can also hire out a sample drive to ensure the predicted savings are being achieved.

Design of a motor control panel – where necessary, we can design, build and install the complete control system to run one or more motors.

Installation and commissioning – we offer full installation and commissioning services including but not limited to setting up the inverter with the motor, or installing the new control panel comprising of the inverter and any other control required.

At RJW we aim to identify the following when considering energy saving using inverters:

- Large motors.
- Motors running over 16 hours a day.
- Motors that lose system efficiency through damping.
- Motors that are not already run on a drive.
- Pump and fan applications that are not already being run from a drive.